WATER IN THE SUBSOIL 117 
as the lower soil layers are moistened, the water is 
enabled, so to speak, to slide down more easily into 
the depths of the soil. 
This is a very important principle for the dry- 
Fig. 31. Dry-farm Kubanka spring wheat, 1909. Fergus Co., Montana. 
Yield, 35 bushels per acre. 
farmer to understand. It is always dangerous to 
permit the soil of a dry-farm to become very dry, 
especially below the first foot. Dry-farms should 
be so manipulated that even at the harvesting season 
a comparatively large quantity of water remains in 
